Levobupivacaine and ropivacaine local anesthetic agents are considered less toxic and tend to replace the use of bupivacaine, reference molecule, but the plasma transition is extremely toxic to patients. However, there is currently no study comparing the benefits of levobupivacaine and ropivacaine in isobaric form injected intrathecally for trauma surgery of the lower limbs. We propose to conduct a prospective, randomized double-blind comparison of the use of these two molecules in spinal isobaric form by evaluating the time and duration of action (sensory and motor block), hemodynamic and ventilatory changes (sympathetic block), and the occurrence of any adverse events.